The balcony was holding about 100 spectators when it fell about 16 feet onto the spectators below, said Col. Alik Betrozov of the Emergencies Ministry.
Rescue workers spent hours searching the rubble and believed they had found all the dead and injured.
The accident occurred in the Trudovye Rezervy indoor sports complex in the Nalchik, 850 miles south of Moscow in the Kabardino-Balkaraya republic. A stadium official said 3,000 spectators were in the stadium at the time.
An assistant to the president of Kabardino-Balkaraya republic, Aleksander Khashkovov, blamed the collapse on the stadium's old age, although the building was only completed in 1994.
A stadium official, who spoke on condition of anonymity, said faulty construction was suspected.
Many of Russia's public buildings are in poor shape; government funding for state facilities all but disappeared after the 1991 collapse of the Soviet Union.